That costume design and look will never happen now that we've had Viper all in green. They will have to go for one of the character's other looks.

Seeing the costumes of Storm, Jean and Rogue. I don't think Polaris' costume will be similar to that one especially if she's gonna be one of the X-Men (they'll probably have the same color scheme for their costumes). So for me, the most important thing about Polaris' appearance if she appears in a X-Men movie, is that they stay true to her hair color.